Hydraulic pump



Patented Dec. 18, 1945 HYDRAULIC PUMP Cyril Alphonso Pugh, Ilford, England, assignor to The Plesse'y Company Limited, Ilford, England,

' a British company Original application May 17, 1943, Serial No. 487,252. Divided and this application June 21, 1944, Serial No. 541,398. In Great Britain July This application is a divisional of my co-pending United States application Serial No. 487,252, filed May 17, 1943, for Hydraulic pumps."

This invention consists in improvements in or relating to hydraulic pumps of the gear type having internal self-lubrication and has for its object to improve the means by which hitherto this self-lubrication has been afforded.

According to the-present invention a hydraulic gear pump comprises in combination a casing consisting of a centre section and two outer sections whereof the centre section is formed as a pump chamber provided with inlet and outlet ports and the outer sections are provided with journal bearings, and a pair of intermeshing pump gears rotatabily mounted in the pump chamber of the said casing, each of said gears having angularly displaced channels provided on its opposite cheeks, each said channel opening at one end to the pump chamber and at the other end to one of the journal bearings whereby the ends of the channels will be brought periodically and successively into communication with the outlet from the pump chamber thereby to receive small quantities of fluid on each occasion, which quantities of fluid are forced into the channels to provide pressure pulsations acting alternately on opposite faces of the gears and in addition will pass to the journal hearings to effect lubrication thereof.

Thus, the liquid in conjunction with which the pump is operating is enabled not only to provide internal lubrication for the pump bearings, but also by the position in which the ducts are situated will provide pressure pulsations occurring alternately on opposite faces of the gears which assists in emcient lubrication.

In order that the invention may be more clearly understood a preferredembodiment of the invention will now be described in which- Figure 1 is a central section through the pump in a plane containing the axes of the pump gears;

Figure 2 is a section on the line 2-2 of Figure l, and

Figure 3 is a perspective view of a portion of one of the gears.

Like reference numerals indicate like parts in all the figures of the drawing.

In the example illustrated each end section l and I! is provided with journal bearings l2 and I3 for the pump spindles l4 and I5 and these bearings are provided with flanges lfi'overlying the inner surfaces of the end sections,the flanges being made of exactly the same diameter as the gears ii and 18 carried respectively by spindles 1 Claim. (01. 103-126) I4 and IS. The centre section is is chambered to fit tightly over the journal flanges l6 and thus in conjunction therewith to provide working chambers for the gears. Laterally on each side of the line of intersection of the gears the centre section is formed with inlet and outlet ports 20 and 2| respectively one on one side and the other on the other side respectively and these ports communicate with similar ports extending, though not shown, through end section II in directions parallel with the axes of' the gears. These two ports open at 22 and 23 respectively with opposite sides of a spring-controlled pressure relief valve 24, the valve chamber 25 of which is accommodated within this end section. Other ducts-26 and 21, also within end section II and leading from the bottoms of the recesses in which the journals are received, are ported into the relief valve casing on the low pressure side of valve 24.

Lubricating ducts I28 will be formed as shallow channels cut into opposite walls of the cheeks of the gears, One duct in each wall of each ear. These ducts are disposed tangentially and in each they are arranged 180 apart and the gears are soassembled that as between one gear and the other the ducts are only apart. Thus as the gears rotate, the ducts will 'come successively into communication with the outlet or pressure conduit and inconsequence small quantities of fluid will on each occasion be forced through the ducts into the journal bearings. Moreover, if, in each gear,rducts I28 are provided one in each side face of the gear and these ducts are spaced out of phase, pressure pulsations will occur acting alternately on the opposite gear faces and will tend to assist in centralising the gears within the casing.

As the gear spindles are hollow by reason of axial passages 3i formed through them, the liquid passing over the bearing surfaces at one end -(i. e. the left-hand side in Figure 1) will be forced through the hollow spindles towards the conduits 26 and 21 in the opposite end section H which communicate with the low pressure side of the relief valve, whereas liquid entering the ducts such as petrol or paraiiin: but although the invention is designed primarily for this purpose, it is not limited to this use as it may be employed for dealing with any hydraulic fluids which of their own nature can serve to lubricate the running arts of the pump.

I claim:

A hydraulic gear pump comprising in combination a casing consisting of a centre section and two outer sections, whereof the said centre section is formed as a pump chamber provided with inlet and outlet ports and the outer sections are provided with Journal bearings, a pair of intermeshing pump gears rotatably mounted in the pump chamber of the said casing, each oi said gears having at least one channel provided on each'oi its opposite cheeks with the channel in one cheek angularly displaced relatively to that in the other cheek, and each such channel opening substantially throughout its length in the face of the said cheek and opening also atone end to the pump chamber and at the other end to one or the Journal bearings, whereby the ends of the channels willbe brought periodically and successively into communication with the outlet 7 irom the pump chamber thereby to receive successive small quantities or fluid as the gears rotate, which quantities of fluid are forced into the channels to provide pressure pulsations acting alternately on opposite faces of the gears,

and in addition will pass to the journal bearhills to eilect lubrication thereof.

CYRIL ALPHONSO PUGH. 

